394 DR. J. B. HICKS ON THE ORGANS 
where the antennæ of the Pediculus of the Crow are represented. Two organs are found 
on each joint, except the last two. In the Pediculus of the Dog the organs are very 
large; they are shown in profile at V. fig. 1 b. 
Pulex also has them on each joint, as seen at V.fig.2. An enlarged view of those of 
the Pulex of the Mouse is shown in fig. 3. 
Having now detailed all the principal facts I have been able to secure since my last 
paper, I shall again endeavour to point out the great advantage to be derived from the 
process of bleaching which I described at that time, without which it would have been 
impossible, by reason of the depth of colour of the insect-integument, to have made such 
advances upon our previous knowledge. It is for this reason that I have no doubt the 
opinions of the naturalists I mentioned at the beginning of this communication would 
have been different, had they known the precise nature of the organs behind the closed 
pores; for it does seem to me impossible that the essential nature of an olfactory organ 
should be included in the structures just mentioned, and that odorous particles could 
pass, first through a membrane, sometimes even spinous, then through a cavity filled 
with fluid, and thirdly through another membrane to reach the extremity of a nerve, 
On the other hand, it is not difficult to conceive that such a structure would be well 
suited to the transmission of sound, upon the principles pointed out by Müller; and the 
numerous modifications of these antennal organs especially to be found in the Hymeno- 
ptera, seem to form an additional reason for supposing them to be auditory—namely, 
that they may give the insects a power of appreciating sounds of various pitch. 
Amongst entomologists, some misconception as to the nature of the antennæ has 
arisen from their not duly considering, in their observations on the habits of insects, that 
the antenna has (whatever other function it possesses), in a great number of insects, å 
faculty of feeling superadded, at least in those insects whose antennæ are tolerably mobile. | 
There can be no doubt that most of the Hymenoptera use them as tactile organs; and I 
am sure that the Honey-bee, Andrena, and the Ichneumonide do so continually, though - 
most writers have considered that the numerous movements of the antennæ of the Ich- 
neumons are for the purpose of smelling; but I am confident that strict observation 
would confirm my opinion that these motions are for feeling—and thus to enable the 
Insects to detect the opening of the holes in which the larvæ they are seeking reside ; 
and that the antenna could be used as well for hearing any noise the larvæ made, as for 
smelling out their position. The Ant has been quoted as an instance strongly showing 
E pa — pe ee for smelling, as is manifested in the power of mutual dec 
vit agus are 3 "eps Last summer I had opportunities of oe 
duals met one another " ; ee ege pe brom oe bt 
their antennæ into conta s be er | 
palpi together, and we u es ERDE Fe er ad pec 
never touched: each other à ES ee = — = re it is 
SM to my; bat I à Ep ve What means they communicated their thoug 
dd = uspect the palpi played the most important part. + 
arks made in this paper, as well as from the observations 
